In a liquid crystal display device (display device), a display panel is of non-light emitting type; accordingly, usually, a backlight device (illumination device), which shines light onto the display panel, is incorporated. As such a backlight device, a backlight device of direct type is known, which comprises a plurality of LEDs (light emitting element) and a reflecting sheet that reflects light emitted from the LED to a display panel.
FIG. 7 is a cross-sectional view showing schematically a structural example of a conventional display device that comprises a backlight device of direct type that includes a plurality of LEDs and a reflecting sheet. FIG. 8 and FIG. 9 are each a cross-sectional view showing a structure around the LED of the conventional display device shown in FIG. 7. As shown in FIG. 7, a display device 1001 comprises a liquid crystal display panel 1002 and a backlight device 1010 that shines light onto the liquid crystal display panel 1002. The backlight device 1010 includes: a plurality of LEDs 1011; a mounting, board 1012 on which the plurality of LEDs 1011 are mounted; a plurality of diffusing lenses 1013 that diffuse light emitted from the LEDs 1011; a reflecting sheet 1014 that reflects light emitted from the LEDs 1011 to the liquid crystal display panel 1002 side; a diffusing plate 1015 and a plurality of optical sheets 1016 that are disposed in front (the liquid crystal display panel 1002 side) of the diffusing lens 1013; and a chassis 1017 that houses the LEDs 1011, the mounting board 1012 and the like.
As shown in FIG. 8, the diffusing lens 1013 is fixed to the mounting board 1012 to cover the LED 1011. The reflecting sheet 1014 is provided with a through-hole 1014a through which the diffusing lens 1013 is disposed, and disposed on the mounting board 1012. Besides, the reflecting sheet 1014 is fixed to the mounting board 1012 by means of a rivet 1020 or a not-shown adhesive layer (double-coated tape or the like).
In the case of using the rivet 1020, the rivet 1020 is often disposed at a position far from the LED 1011 not to block the illumination light. Because of this, as shown in FIG. 9, there is a case where the reflecting sheet 1014 is raised around the mounting board 1012. In this case, there is a disadvantage that part of the light emitted from the LED 1011 goes under the reflecting sheet 1014; whereby brightness unevenness easily occurs and light loss occurs.
To improve the above disadvantage, illumination devices are proposed, which alleviate the rising of a reflecting sheet by means of a diffusing lens (e.g., patent documents 1 and 2).
The patent document 1 discloses a light source device (illumination device) that has: a plurality of light emitting diodes (light emitting elements); a light emitting diode board (mounting board) on which the plurality of light emitting diodes are mounted; a diffusing lens that diffuses the light emitted from the light emitting diode; and a reflecting sheet that is provided with a through-hole, through which the diffusing lens is disposed, and disposed on the light emitting diode board.
The diffusing lens includes a lens portion that diffuses the light emitted from the light emitting diode and a positioning protrusion (fixing portion) that protrudes from the lens portion to the light emitting diode board to be fixed to the light emitting diode board. The lens portion is provided with a convex portion that protrudes in parallel with a surface of the light emitting diode board. The convex portion cooperates with the light emitting diode board to sandwich the reflecting sheet, thereby alleviating the rising of the reflecting sheet.
The light source device in the patent document 1 alleviates the rising of the reflecting sheet by means of the diffusing lens; accordingly, it is possible to somewhat alleviate the reflecting sheet being raised from the light emitting diode board around the light emitting diode. Because of this, it is possible to somewhat alleviate the light emitted from the light emitting diode going under the reflecting sheet, and it is possible to somewhat alleviate the brightness unevenness and light loss.
The patent document 2 discloses a light emitting device (illumination device) that comprises: a plurality of light emitting elements; a board (mounting board) on which the plurality of light emitting elements are mounted; a luminous flux control member (diffusing lens) that diffuses the light emitted from the light emitting element; and a reflecting sheet disposed on the board.
The luminous flux control member includes: a lens portion that diffuses the light emitted from the light emitting element; and three supporting, legs that protrude from the lens portion toward the board. Two supporting legs are fixed to the board. The one remaining supporting leg is formed shorter than the two supporting legs and disposed on the reflecting sheet. The one supporting leg cooperates with the board to sandwich the reflecting sheet, thereby alleviating the rising of the reflecting sheet.